The present invention is directed to methods and devices for testing telephone circuits, and more particularly to a method and device for testing a public switched telephone network (PSTN) circuit in which a caller relies on caller identification (hereinafter "caller ID") information available through the telephone system to complete a ringback test to the caller.
With reference to FIG. 1, ringback testing devices are known in the art as means for testing a PSTN circuit. By using such a device 10, a subscriber or craftsperson (both are hereinafter referred to as a "caller") with telephone handset 12 or test set 14 may test the circuit by having the caller's telephone number called from another part of the circuit after the caller goes on hook: this is known as a ringback test. Ringback tests verify continuity and operation of dial-up lines between the telephone central office 16 and the caller 12 or 14. They provide a relatively complete test of a circuit from the caller's connection, through the PSTN circuit, including office equipment in the telephone central office 16 capable of providing telephone service ("OE" in the figures), and back to the caller's connection. Ringback tests may also be conducted of circuits in customer premises equipment (CPE) and references herein to tests of circuits in public switched telephone networks include tests of CPE circuits, and tests from one CPE to another CPE.
One ringback test device is described in U.S. Pat. No. 4,764,949 issued Aug. 18, 1988 to Faith, et al., and assigned to the assignee hereof, that is incorporated by reference. One of the problems solved by the device described therein is the method by which the caller's telephone number is obtained so that the ringback test may be completed. Callers, such as craftspersons working on a telephone line with a butt-in test set and telephone installers, may not know the telephone number associated with the particular wire on which they are working. As suggested by Faith, et al., the telephone number may be obtained when the caller calls a prescribed ringback access code that accesses the ringback test device 10 at the telephone central office. Upon receipt of the ringback access code, the device 10 signals a specialized trunk facility 18 within the telephone central office 16, known as a toll trunk or outgoing trunk circuit, causing it to transmit a message that identifies the caller's telephone number. The number is stored at the ringback test device 10 and the caller is thereafter instructed to disconnect from the circuit (go on hook). When the caller is disconnected the test device 10 sends a signal to the central station 16 instructing it to dial the stored telephone number. The test is successful if the caller's telephone rings. However, there are some problems with this method in that the use of toll trunks may be costly and the toll trunks may not always be available for testing. Further, the test unit is located at the central office, and thus is available only when the central office is equipped with the test device. It is desirable to have a portable ringback tester that can be used when a tester is not installed at the central office, or to avoid toll charges that may be associated with use of someone else's (e.g., the phone company) tester.
Accordingly, it is an object of the present invention to provide a novel method and system for capturing a caller's telephone number for a ringback test that obviates the problems of the prior art.
It is another object of the present invention to provide a novel method and system for using caller ID information to conduct tests of a circuit in a telephone network.
Caller ID is a service available to subscribers in telephone systems incorporating the out-of-band signaling system protocol Signal System 7 (SS7). The caller ID service in its current embodiment provides the caller's telephone number, time of call, caller's name, and other information in a signal that is transmitted from the central office to a called subscriber during the three second silent interval between the first and second rings of the called subscriber's telephone. The caller ID information is transmitted conventionally through the telephone network in a standard serial binary format with an asynchronous frequency-shift keying (FSK) modem-like transmitter. With an appropriate receiver, the caller ID information may be displayed to the called subscriber so that the called subscriber may determine who is making the call before going off hook to answer the call. Subscribers may elect not to have their caller ID information transmitted by adding a privacy indicator (e.g., the letter "P") to the caller ID information, such as when a telephone number is "unlisted". If the caller ID information is not available, as when the caller ID service is not provided or when the caller is out-of-area (such as may be applicable to CPE caller ID systems), an out-of-area/unavailable indicator may be provided (e.a., the letter "O") instead of the caller ID information. Additional information about caller ID is available in Bellcore Technical Reference TR-TSY-000031, Issue 3, January 1990 (Bellcore, Morristown, N.J.) that is incorporated by reference.
It is still another object of the present invention to provide a novel method and test device for conducting tests of a telephone circuit in which caller ID provides a caller's telephone number and/or name and a ringback test is conducted without resort to a specialized trunk facility.
It is yet another object of the present invention to provide a novel portable test device that takes advantage of caller ID services to conduct telephone network tests, including ringback tests, tests of caller ID features such as the privacy and out-of-area indications, and tests connections to other numbers.
It is a further object of the present invention to provide a novel telephone circuit test device that takes advantage of caller ID services to conduct telephone circuit tests, and that includes the ability to receive manually entered telephone numbers from a caller.
It is still a further object of the present invention to provide a novel telephone circuit test device in which caller ID information is provided to a visual display device for conducting telephone circuit tests.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.